Sterile containment welding device with self-monitoring heater unit for plastic tubes

ABSTRACT

A sterile containment welding device includes a self-monitoring heater unit upstream from the space between the tube receiving channels. The wafer is positioned in the unit and mounted for movement through the unit prior to moving through the space. The self-monitoring heater unit includes a heater which heats the wafer and a temperature sensor for monitoring the temperature created by the self-monitoring heater in a rapidly alternating sequence so that the wafer is heated to a predetermined temperature before being moved into the space and contacting the plastic tube or tubes.

CROSS-REFERENCE TO RELATED APPLICATION

This application is a continuation in part of application Ser. No.09/036,775, filed Mar. 9, 1998, now U.S. Pat, No. 6,020,574.

BACKGROUND OF THE INVENTION

Sterile containment welding devices are known for connecting anddisconnecting plastic tubes. Examples of such devices are found in U.S.Pat. Nos. 5,256,229, 5,279,685 and 5,397,425. In general, such devicesinclude a pair of tube holders which would be in alignment with eachother. Each of the tube holders has a base with the tube receivingchannel into which a plastic tube would be placed. Each tube holder alsoincludes a clamping jaw having a ram and anvil located above thechannel. Thus, for example, when a tube is placed in the channel theclamping jaw is moved into locking engagement with the base and theanvil presses against the tube. In one practice of such devices eachtube is placed in its channel in a bent condition by being bent uponitself with the bend of the tube extending outwardly from the outer edgeof the channel. Thus, in a connect procedure the pair of bent ends wouldbe disposed toward each other with each bent section in alignment with acorresponding bent section of the opposite tube holder. The connectprocedure is achieved by passing a heated wafer between the two benttube ends which causes the tube ends to melt so that a tube section fromeach tube can be pressed into contact with a corresponding tube sectionfrom the other tube and thereby join the two sets of tube sectionstogether.

It is known to include in such devices a thermocouple which monitors thetemperature of the heater device so that there is assurance that thewafer will be heated to the desired predetermined temperature. Inoperation when the device is actuated the heater operates continuouslyto raise its temperature until the desired temperature is reached. Thethermocouple, which is separate from the heater, monitors thetemperature rise to sense reaching the desired temperature.

SUMMARY OF THE INVENTION

An object of this invention is to provide such a sterile containmentwelding device with a self-monitoring heater which functions not only toheat the wafer but also to monitor the heating process.

A further object of this invention is to provide such a self-monitoringheater unit which functions in a rapid sequence of alternatinglymonitoring the heater and performing its heating function.

A still further object of this invention is to use such self-monitoringheater for devices other than sterile containment welding devices.

In accordance with the preferred practice of this invention a sterilecontainment welding device includes a pair of alignable tube holderseach of which has a tube receiving channel with the channels beingspaced from each other. A wafer is provided for selective movement intothe space to connect/disconnect the tube or tubes mounted in thechannels and extending into the space. In accordance with this inventiona self-monitoring heater unit is provided upstream from the space. Thewafer is mounted for movement through the heater unit prior to movementthrough the space. The unit comprises a heater for heating the waferwhen the wafer is disposed in the unit and further includes atemperature sensor for monitoring the temperature created by the unit.As a result, the wafer is raised to its predetermined temperature beforebeing moved into the space.

In a preferred practice of the invention the heating and monitoringfunctions place in rapid sequence such as being a millisecond for eachfunction. More preferably the heating period is substantially longerthan the monitoring period. Preferably, the self-monitoring heater unitis a ribbon etched with a trace to act as a heater and which includes athermocouple junction for the sensor.

THE DRAWINGS

FIG. 1 is a side elevational view partly broken away showing a sterilecontainment welding device in accordance with this invention;

FIG. 2 is a side elevational view of the self-monitoring heater assemblyincorporated in the device of FIG. 1;

FIG. 3 is a exploded perspective view of the self-monitoring heaterassembly shown in FIG. 2;

FIG. 4 is a top plan view of the self-monitoring heater unit shown inFIGS. 2-3;

FIG. 5 is an enlarged side elevational view showing the etching tracefor the self-monitoring heater unit of FIGS. 2-4; and

FIG. 6 is a graph showing the sequence of operation of theself-monitoring unit of this invention.

DETAILED DESCRIPTION

The present invention is directed to sterile containment welding devicesfor connecting or disconnecting plastic tubes. Such devices are known inthe art. Examples are described in U.S. Pat. Nos. 5,256,229, 5,279,685,and 5,397,525, all of the details of which are incorporated herein byreference thereto. In particular, the later described self-monitoringheater unit is incorporated in the type of device shown in detail inU.S. Pat. No. 5,279,685.

In general, the sterile containment welding device 10 includes a basemember 12 and a pivotally mounted upper member 14. The base member andupper member maybe considered as comprising a pair of tube holders eachof which has a tube receiving channel 16 into which a tube or tubesection 18 would be located in a known manner. The tube 18 is in aflattened condition by manipulating the handle 20 which actuates aclamping jaw 22 having an anvil 24 which is locatable over the channel16 for pressing against the tube. The outer end of the channels arespaced from each other so that a wafer 26 shown in phantom in the righthand portion of FIG. 2 may pass through the space and heat two tubesections for welding or connect purposes or melt through a tubeextending across the channels for disconnect purposes. Wafer 26 which isshown in full lines in the center of FIG. 2 is mounted in a holder 28received a carriage connected to a drive 30 and moved by reversiblemotor 32 known manner in a forward direction as indicated by the arrow34. The carriage is then returned to the start position. The wafer isheated prior to moving to the spacing to effect the connect/disconnectoperation.

In accordance with this invention a self-monitoring heater unit 36 isprovided to form the dual functions of heating the wafer and monitoringthe heating temperature to assure that the wafer is heated to itsdesired predetermined temperature.

As illustrated, the self-monitoring heater unit 36 comprises a pair ofspaced, parallel thermocouple ribbons 38 which are formed by having anetched trace 40 as best shown in FIGS. 3 and 5. Each thermocouple ribbonis laminated onto a thick support member 42 such as a silicone tape. Inthe preferred practice of this invention a flat E-type thermocoupleribbon composed of Cu/Ni and Ni/Cr (Chromel-Constantan) with theindividual legs of the thermocouple sized so that the electricalresistances equilibrate out to about 5.68±10% ohm resistance. Thethermocouple trace experiences a temperature rise causing a voltagechange that can be measured. In accordance with this inventionutilization is made of the etched trace 40 so that it also functions asa heater. The trace 40 includes a thermocouple junction 44 to permit themonitoring to take place. In this manner there is first a heatingoperation and then a measuring or monitoring operation. The switchingtakes place by appropriate electronics at speeds of milliseconds. Forexample, there is one millisecond of the unit 36 functioning as a heaterwith the next millisecond functioning as a thermocouple when the unit 36functions as a heater. The temperature rises then for the nextmillisecond. There is then a monitoring of the temperature with thetemperature again rising in the subsequent millisecond until the desiredtemperature is reached. When the desired temperature is reached, thewafer 26 is heated to that temperature by being contacted on each sideby an etched trace 40. The heated wafer then moves from unit 36 to thespacing between the tube holding channels.

In the preferred practice of the invention the thermocouple ribbon isabout 0.002 inches thick. The polarity of the thermocouple is marked byetching a hole on the constantan or negative side of the thermocouple.FIG. 4 also illustrates the positive conductor wire 47 for theelectrical conductor cables 46. The cables 46 are mounted to printedcircuit board 45 as best shown in FIG. 1. The type-E thermocouple ribbonis preferably laminated onto a 0.001 inch thick silicone tape. The traceart work is registered with respect to the thermocouple junction 44. Thetrace is then etched followed by a covered lamination of 0.001 inchthick silicone tape.

As shown in FIG. 3 each ribbon 38 is connected to a cable 46 at one endthereof. A leaf spring 48 is provided for each ribbon 38 to urge the tworibbons toward each other. Each leaf spring 48 is mounted in a springclamp 50 on an insulator support 52. A pair of screws 49 extend throughthe holder 28 and press against each spring 48 to control the spacingbetween the two parallel sections of unit 36 particularly the traces 40.Screws 49 thereby assure that the spacing is sufficient to allow wafer26 to pass between the two traces 40 and yet be close enough to assurethat there rubbing contact by each side of the wafer 26 and itsrespective heater trace 40.

Wafer 26 may be of any suitable construction and preferably is of theconstruction shown and described in U.S. Pat. Nos. 5,525,186 and5,397,425, the details of which are incorporated herein by referencethereto.

In the practice of the invention the wafer 26 would be mounted in theholder 28 between the closely spaced trace portions 40,40 of theself-monitoring heater unit 36. While the wafer is in this upstreamposition the unit 36 begins its rapid sequence of heating andtemperature monitoring in the sequential steps illustrated in FIG. 6until, for example, a predetermined temperature such as 300° C. isreached. FIG. 6 illustrates the sequence of heating and temperaturemonitoring to take place wherein the heating period of time (which mightbe considered a first fixed period of time) is nine times longer thanthe monitoring period of time (which might be considered a second fixedperiod of time). Thus, this rapid sequence permits the wafer or heatapplying tool to reach a predetermined temperature in an accuratemanner. With this practice of the invention the alternating sequence isa long fixed period of heating and a short period of monitoring. Becausethe wafer 26 in holder 28 is in the unit 36 with each side of the wafer26 contacted by the heater element or trace 40 of unit 36, the wafer israised to its predetermined temperature. The wafer is removed by thecarriage from holder 28 and then moved downstream in the direction ofarrow 34 away from unit 36 and into the space between the tube receivingchannels 16 in a known manner.

The present invention thus provides a combined heater and thermocouplewhich results in a self-monitoring heater which detects the temperaturerise of its own heating elements in a rapid sequential manner toeffectively heat a wafer for thereby improving the heater performance ofthe sterile containment welding device.

The present invention is unique in that it utilizes the same structurewhich heats a device, such as a heat applying tool or in the preferredpractice a wafer, and which alternately monitors the temperature of thetool so that there can be a reliable accurate reaching of thatpredetermined temperature. The same structure undergoes a sequencewhere, for one period of time, the structure has its heating function(without temperature monitoring) and then the same structure which hadfunctioned as a heater no longer has that function, but insteadfunctions as a temperature monitor. This sequence of heating andtemperature monitoring takes place in a rapid manner during millisecondtime periods.

The invention may be practiced by utilizing the same structure in analternate manner for both heating and temperature monitoring. Forexample, the invention utilizes a thermocouple ribbon in such a mannerthat a continuous thermocouple junction runs down the center of theribbon. A section of the ribbon is laminated onto a substrate and etchedinto a heater trace pattern leaving a thermocouple junction in themiddle of the heating traces. This effectively creates a flexible heaterthat can sense its own temperature.

Although the invention has been described with particular reference tothe heating of plastic tubes, the invention may have other applicationswhere a heating sequence is periodically monitored for temperaturedetermination. The following are some examples where the invention couldbe practiced. The heating/monitoring sequence could be used for theheating of automobile seats. In such practice the user would press theseat/heat button to initiate the heating/monitoring sequence until thedesired temperature is reached. Another practice of the invention couldbe in the de-icing of aircraft wings. A further practice could be forinstruments of small aircrafts. In such small aircrafts there is a needto maintain the instruments in a sufficiently warm condition. Theinvention could be used for assuring that the proper temperature isreached. A still further practice could be to keep seals warm, such asin spacecraft launching.

In the preferred practice of the invention the heat applying tool ismoved to the heating site after the predetermined temperature has beenreached. The invention may also be practiced where the heat applyingtool is located at the heating site during the heating/monitoringsequence. The raising of the temperature of the heat applying tool wouldbe discontinued once the predetermined temperature is reached. Thiscould be done by either stopping the heating function or by simplysupplying enough heat to maintain a generally constant temperature.

As should thus be apparent, the invention has wide application where theself-monitoring heater is used to assure reaching a predeterminedtemperature.

What is claimed is:
 1. In a device for performing a heating operationincluding a heat applying tool for heating an object at a heatinglocation, and a heater for heating said heat applying tool, theimprovement being in that said heater includes a self-monitoring heaterunit in selective contact with said tool, said self-monitoring heaterunit including structure for alternately in a rapid sequence heatingsaid tool and then monitoring the temperature of said tool until apredetermined temperature has been reached, and conveying structure formoving said tool to said heating location after said predeterminedtemperature has been reached.
 2. The device of claim 1 wherein saiddevice is a sterile containment welding device for plastic tubes havinga pair of alignable tube holders, each of said tube holders having abase with a tube receiving channel which includes an outer end whereby aplastic tube may be placed in said channel and extend outwardly of saidouter end, said outer ends of said tube holders being spaced from eachother to create a space between said tube holders, said space being saidheating location, said heat applying tool being a wafer mounted forforward movement through said space for contacting a portion of a tubeextending outwardly of said outer end of each of said channels, and saidself-monitoring heater unit being upstream from said space with respectto said forward direction of movement.
 3. The device of claim 1 whereinsaid self-monitoring heater unit comprises a ribbon having an etchedtrace to function as a heater and having a thermocouple junction.
 4. Thedevice of claim 3 wherein said ribbon is a Chromel-Constantan ribbon. 5.The device of claim 3 wherein said ribbon is laminated onto a tapesupport member.
 6. The device of claim 5 wherein said unit includes apair of said ribbons located adjacent to and parallel to each other andspaced apart a distance sufficiently close whereby each of said ribbonscontacts a respective side of said tool when said tool is locatedbetween said ribbons.
 7. The device of claim 6 including spring membersfor urging said ribbons toward each other.
 8. The device of claim 7including space adjusting members movably mounted against said springsfor controlling the spacing between said traces.
 9. The device of claim8 wherein said tool is mounted on a movable carriage, and said toolhaving a start position in a holder at said unit.
 10. The device ofclaim 9 wherein each of said traces includes legs having an electricalresistance of 5.68±10% ohm resistance.
 11. The device of claim 10wherein said sequence is in an alternating millisecond sequence oflonger heating period than monitoring period.
 12. The device of claim 1wherein said sequence is in an alternating millisecond sequence oflonger heating period than monitoring period.
 13. The device of claim 1wherein said ribbon is mounted onto a tape support member, said ribbonbeing a type-E thermocouple having a thickness of about 0.002 inches.14. The device of claim 13 wherein each of said traces includes legshaving an electrical resistance of 5.68±10% ohm resistance.
 15. Thedevice of claim 1 wherein said unit includes a pair of said ribbonslocated adjacent to and parallel to each other and spaced apart adistance sufficiently close whereby each of said ribbons contacts arespective side of said wafer when said wafer is located between saidribbon.
 16. The device of claim 15 including spring members for urgingsaid ribbons toward each other.
 17. The device of claim 16 includingspace adjusting members movably mounted against said springs forcontrolling the spacing between said traces.
 18. In a device forperforming a heating operation including a heat applying tool forheating an object at a heating location, and a heater for heating saidheat applying tool, the improvement being in that said heater includes aself-monitoring heater unit in selective contact with said tool, saidself-monitoring heater unit including structure for alternately in arapid sequence heating said tool and then monitoring the temperature ofsaid tool until a predetermined temperature has been reached, saidself-monitoring heater unit comprising a ribbon having an etched traceto function as a heater and having a thermocouple junction, said unitincluding a pair of said ribbons located adjacent to and parallel toeach other and spaced apart a distance sufficiently close whereby eachof said ribbons contacts a respective side of said tool when said toolis located between said ribbons, and said sequence being in analternating millisecond sequence of longer heating period thanmonitoring period.
 19. In a method for performing a heating operationincluding providing a heat applying tool which heats an object at aheating location and heating the heat applying tool with a heater, theimprovement being in using a self-monitoring heater unit in the heater,selectively contacting the tool with the self-monitoring heater unit,using the same self-monitoring heater unit to rapidly alternately heatthe tool and monitor its temperature, performing the heating andmonitoring in a millisecond sequence of longer heating period thanmonitoring period.
 20. The method of claim 19 including moving the toolto the heating location after a predetermined temperature is reached.